KR20070004985A - Mehtod and apparatus for countering mold deflection and misalignment using active material elements - Google Patents

Abstract

Method and apparatus for controlling an injection mold having a first surface and a second surface includes an active material element configured to be disposed between the first surface and a second surface. The active material element may be configured to sense a force between the first surface and the second surface, and to generate corresponding sense signals. Transmission structure is coupled to the active material element and is configured to carry the sense signals. Preferably, an active material element actuator is also disposed between the first surface and a second surface, and is configured to provide an expansive force between the first surface and a second surface in accordance with the sense signals. The method and apparatus may be used to counter undesired deflection and/or misalignment in an injection mold. ® KIPO & WIPO 2007

Description

METHOD AND APPARATUS FOR COUNTERING MOLD DEFLECTION AND MISALIGNMENT USING ACTIVE MATERIAL ELEMENTS}

The present invention relates to a method and apparatus for canceling mold warpage and mold misalignment, wherein active material elements are used in injection molding machine equipment (eg, insert stacks) to detect and / or offset warpage in a mold structure. will be. An "active material" is a group of shape changing materials, such as piezo actuators, piezoceramics, electrostrictors, magnetostrictors, shape memory alloys, and the like. In the present invention, they are used in injection molds to offset warpage in the mold structure, improving the quality of the molded article and the life of the mold components and improving the resin sealing. Active material elements may be used as sensors and / or actuators.

Active materials are characterized as transduces that can convert one form of energy into another. For example, a piezo actuator (or motor) converts input electrical energy into mechanical energy causing a dimensional change of the device, while a piezo sensor (or generator) converts mechanical energy-a change in the dimensional shape of the device. To energy. One example of a piezoceramic transducer is shown in US Pat. No. 5,237,238 to Berghaus. Marco Systemanalyse und Entwicklung GmbH is a supplier of piezoelectric actuators in Dau-Haus-Weckler Strasse 2, De-85221, Germany, whose advertising materials and websites are Describe the device. Typically the application of a 1000 volt potential to the piezoceramic insert “grows” it to approximately 0.0015 ”/ inch in thickness. The other source, Mid Technology Corporation of Medford, Maine, is a magnetostrictive and shape memory. It has various active materials, including alloys, and its advertising materials and websites describe such devices, including material specifications and other published details.

1 shows a schematic view of a multiple cavity preform mold. The injected molten plastic is divided into channels contained in multiple manifolds 11 which flow through the sprue bush 10 and are connected to individual nozzles 12 for each mold cavity 13. The manifold 11 is included in cutouts made in the manifold plate 12 and the manifold support plate 15. Although there is usually a support (not shown) that extends through the manifold structure connecting the manifold plate 14 and the manifold support plate 15, the combined structure of the half halves of the mold is less rigid than desired.

2 shows a form in which the manifold plate 11 can be bent at 16 under molding conditions in an exaggerated form. The effect of this warp unevenly supports the multiple forming stacks 17, producing parts of varying quality for each stack. It is desirable to provide a means to minimize manifold plate warpage and provide uniform support for all forming stacks.

U. S. Patent No. 4,556, 377 to Brown discloses a self-centering mold stack design for thin wall applications. Spring loaded bolts are used to hold the core insert in the core plate while allowing the core insert to align with the cavity half of the mold via interlocking taper. Although Brown discloses a means of improving alignment between the core and the cavity and reducing the effect of the core shift (“offset”), there is no disclosure of actually measuring and correcting such shifting in an active manner.

It is an advantage of the present invention to provide an injection molding machine apparatus and method which overcomes the above mentioned problems and provides an effective and efficient means for detecting and / or correcting warpage and misalignment in molds provided in injection molding machines.

According to a first aspect of the invention, a structure and / or function is provided for an injection mold having a core and a core plate. The active material sensor is configured to be positioned between the core and the core plate and is configured to sense a force between the core and the core plate and generate a corresponding sensing signal. The wiring structure is configured to be coupled to the active material sensor in use to deliver a sense signal.

According to a second aspect of the invention, a structure and / or function is provided for a control device for an injection mold having a first surface and a second surface. The active material sensor is configured to be disposed between the first surface and the second surface of the injection molding machine and senses the compressive force between the first surface and the second surface to generate a corresponding sensing signal. The transmission structure is configured to transmit a sense signal from the active material sensor in use.

According to a third aspect of the invention, a structure and / or step is provided for controlling warpage between first and second surfaces of an injection molding machine. The piezoceramic actuator is configured to be disposed between the first and second surfaces of the injection molding machine to receive an actuation signal and to generate an expansion force between the first and second surfaces. The transmission structure is configured to transmit an actuation signal to the piezoceramic actuator.

Exemplary embodiments of the presently preferred configuration of the present invention will be described with reference to the accompanying drawings.

1 is a schematic diagram of a multicavity preform mold.

Figure 2 is a schematic diagram of a multi-cavity preform mold bent by injection molding under mechanical clamping.

3 is a schematic diagram of a core lock style preform forming stack comprising an embodiment according to the present invention.

4 is a schematic view of a cavity lock style preform forming stack comprising an embodiment according to the present invention.

5 is a schematic of an exemplary thin wall container forming stack showing core shift problems.

6 is a schematic of an exemplary thin wall container forming stack comprising an embodiment according to the present invention.

7 is a schematic plan view of a thin wall container forming stack including an embodiment according to the present invention.

8 is a schematic of an exemplary thin wall container forming stack incorporating another embodiment of the present invention.

1. Introduction

The present invention will be described with respect to some embodiments in which the active material element serves to detect and / or correct warpage and misalignment of the injection mold. However, active material sensors and / or actuators may be located at any location in the injection molding apparatus where misalignment and / or sealing problems may occur. Other applications for such active material elements include (1) "methods and apparatus for assisting with ejection from an injection molding machine using active material elements", and (2) "adjustable hot runner assembly seals and tips using active material elements. Method and apparatus for providing height ", (3)" Method and apparatus for controlling vent gap using active material element ", (4)" Method and apparatus for locking mold component using active material element ", (5)" methods and apparatus for vibrating melt in an injection molding machine using active material elements ", (6)" methods and apparatus for injection compression molding using active material elements ", and (7) Reference is made in the related application entitled "Control System for Using Active Material Elements in Molding Systems," all of which are filed concurrently with the present application.

In the following description, the piezoceramic insert will be described as the preferred active material. However, other materials from the group of active materials such as magnetostrictive and shape memory alloys can also be used in accordance with the present invention. A list of possible other active materials and their properties is presented below in Table 1, and any of these active materials may be used in accordance with the present invention.

Comparison of Active Materials material Temperature range (℃) Nonlinearity (history) Structural integrity Cost / volume. ($ / Cm 3) Technical maturity Piezoceramic PZT-5A -50-250 10% Brittle ceramic 200 Commercial Piezo-Single Crystal TRS-A - <10% Brittle ceramic 32000 Research Whole warp PMN 0-40 Brittle ceramic 800 Commercial Magnetostrictor or terphenol-D -20-100 2% Brittle 400 Research Shape memory alloy nitinol Temperature. Control height OK 2 Commercial Magnetic activation SMA NiMnGa <40 height OK 200 For preliminary research Piezopolymer cgPVDF -70-135 > 10% Good 15 * Commercial

(Source: www.mide.com)

2. Structure of First Embodiment

A first preferred embodiment of the present invention is shown in FIG. 3 showing a core lock injection molding machine preform molding stack 101. The stack includes a gate insert 120, a cavity 121, neck ring halves 122a and 122b, a core 123 and a core sleeve 124. The core sleeve 124 is used by several spring loaded fasteners (eg, bolt 126, washer 127 and spring washer (bellville) 128) to fasten the sleeve to the core plate 129. Has a flange 125. The core 123 has an annular channel 130 to accept an annular piezoceramic element 131. The core plate 129 has a wire groove 131 to receive the wiring connecting portion 133 in the element 131. The piezoceramic element 131 may also be driven by radio means (not shown).

The piezo-electric element 131 may comprise a piezo-electric sensor or a piezo-electric actuator (or a combination thereof), for example manufactured by Marco Justem Analogue und Entbiklung GmbH. It may also include any device. The piezoelectric sensor will detect the pressure applied to the element 131 and transmit a corresponding sense signal through the wire connection 133. The piezoelectric actuator will receive the actuation signal through the wire connection 133 and apply a corresponding force between the core plate 129 and the core 123. One or more piezoelectric sensors are provided to sense pressure from any desired location (or any other location) in the annular groove 130. Similarly, one or more piezoelectric actuators may be provided and mounted continuously or in series with each other and / or with the piezoelectric sensor in order to perform extended movements, angular movements, etc. of the core 123 relative to the core plate 129. May be

The piezoceramic actuator is preferably a single actuator that is annular or cylindrical. According to the presently preferred embodiment, the actuator increases in length by approximately 0.15% when a voltage of 1000V is applied through the wiring 233. However, the use of multiple actuators and / or actuators with other shapes may be considered to be within the scope of the present invention, and the present invention should therefore not be limited to any particular configuration of the piezoceramic actuator.

Preferably, one or more separate piezoceramic sensors may be provided adjacent to the actuator (or between any or related surfaces described above) to detect the pressure caused by the injection of the plastic. Preferably the sensor provides a sense signal to the controller 143. Piezoelectric elements (ie piezoelectric sensors and / or piezoelectric actuators) used in accordance with a preferred embodiment of the present invention may comprise any device manufactured by Marco Justem Analyze und Entbiklung GmbH. . The piezoelectric sensor will detect the pressure applied to the actuator and transmit a corresponding sense signal through the wire connection 133, allowing the controller 143 to perform closed loop feedback control. The piezoelectric actuator will receive an actuation signal through the wiring connection 133, change its dimensions in accordance with the actuation signal, and apply a force corresponding to the adjacent mold component to control the mold deflection in an adjustable manner.

Note that a piezoelectric sensor may be provided to sense pressure at any desired location. Likewise, one or more piezoelectric actuators may be provided and mounted continuously or in series to perform extended movements, angular movements, and the like. In addition, each piezoelectric actuator may be divided into one or more arcuate, trapezoidal, rectangular, etc. shapes that may also be controlled separately to provide varying sealing forces at various locations between the sealing surfaces. In addition, piezoelectric actuators and / or actuator segments may be laminated in two or more layers as necessary to effect fine sealing force control.

The wiring connection 133 may be coupled to any desired type of controller or processing circuit 143 to read the piezoelectric sensor signal and / or to provide an actuation signal to the piezoelectric actuator. For example, one or more general purpose computers, special purpose integrated circuits (ASCIs), digital signal processors (DSPs), gate arrays, analog circuits, dedicated digital and / or analog processors, hard-wired circuits, and the like. The piezoelectric element 131 described herein may be controlled or sensed. Instructions for controlling one or more processors may be stored on any desired computer readable media and / or data structures, such as floppy diskettes, hard drives, CD-ROMs, RAMs, EEPROMs, magnetic media, optical media, magnetic-optical media, and the like. It may be.

The use of the piezoceramic element according to the present embodiment allows the various components of the above-described injection mold assembly to be manufactured with low tolerances, thereby reducing the manufacturing cost of the injection molding machine component itself. Previously, a tolerance of 5 to 10 microns was used to achieve a functional injection mold. Additional advantages include the ability to adjust the alignment of casting components, preventing mold warpage and reducing the length of any equipment downtime.

3. Process of the first embodiment

In operation, when the mold is closed and the clamping tonnage is applied to the mold, the forming stack 101 aligns its components as follows. The gate insert 120 is fitted inside the cavity 121 by positioning the diameter portion (not shown), and the cavity female taper 134 is corresponding to the male taper 135 in the neck ring inserts 122a and 122b. ), The neck ring male taper 136 aligns the corresponding female taper 137 in the core sleeve 124, and the core sleeve inner female taper 138 aligns the core male taper 139. At the base of the core sleeve 124 spring-loaded fastening means (biasing means) allow some movement and the core spigot 140 at the core base 126 without jeopardizing the sealing of the core cooling circuit 141. Because of the corresponding tolerances, the core sleeve 124 and the core 123 can be moved to conform to this taper alignment method. The element 131 is preferably slightly thicker than the depth of the annular groove 130 so that there is a slight gap 142, typically less than 0.1 mm, between the base of the core 123 and the core plate 129 when assembled. .

While clamped and during injection of the resin into the cavity, and as the injection pressure builds up and remains inside the cavity, the injection pressure causes the core and core sleeve to exert a force toward the core plate that the element 131 senses as a compressive load. Acts on a protruding region of. The insert will preferably transmit an electrical signal that varies with the force applied thereto. This signal is transmitted to an apparatus (not shown) for processing a signal for communication to the controller 143 which determines whether a command signal for canceling the compressive load should be transmitted. For example, a command signal may be sent to adjust the clamping force or injection pressure or injection speed to vary the conditions in the mold cavity.

Alternatively, element 131 may be used as a motor (force generator) to power (or remove) power to element 131 to expand (or contract) in size and thereby adjust the height of mold stack 101. It may be. In this embodiment, the element 131 preferably comprises an annular cylinder having a length between 55 and 75 mm that can produce an increase in length of approximately 0.1 mm when approximately 1000 V is applied. By controlling the height of each stack 101 individually, variations in the rigidity of the mold structure as a whole and in particular the bending of the manifold plate 114 can occur. For example, in this embodiment, if the individual height adjustment of the stack is within the operating range of each device, typically less than 0.1 mm in this embodiment, then all devices 131 (one per forming stack) are between the stacks. The same voltage may be provided to achieve a balanced load distribution of.

4. Structure of Second Embodiment

4 shows another preform forming stack 102 for a cavity locked stack. The stack includes a gate insert 150, a cavity 151, neck ring halves 152a and 152b and a core 153. The core 153 has several spring loaded fasteners (e.g., bolts 156, washers 157 and spring washers (bellvilles) 158) for fastening the core 153 to the core plate 159. It has a flange 155 used through. Core 153 has an annular channel 160 at its base to accept an annular shaped piezoceramic insert 161. The core plate 159 has a wire groove 162 to accept the wire connecting portion 163 to the element 161, and the wire connecting portion 163 may be selectively connected to the controller 171. There is typically a similar assembly gap 170 of less than 0.1 mm.

Optionally, one or more separate piezoceramic sensors may be provided to detect the pressure caused by the position change inside the mold. These sensors may also be connected to the controller 171 by conduits 163. The piezoelectric element 161 (e.g., piezoelectric sensor and / or piezoelectric actuator) used in accordance with the present invention may comprise any device manufactured by Marco Justem Analyze und Entbiklung GmbH. have. The piezoelectric sensor can detect pressure at various interfaces inside the nozzle assembly and can transmit corresponding sensing signals through the conduits, thereby performing closed loop feedback control. The piezo electric actuator then receives the actuation signal through the conduit and applies a corresponding force. Piezoelectric sensors may be provided to sense pressure from any desired location. Likewise, more than one piezoelectric actuator may be provided in place of any single actuator described herein, and the actuators may be mounted continuously or in series to effect extension movements, angular movements, and the like.

As mentioned above, one of the significant benefits of using the active element insert 161 described above allows for wider manufacturing tolerances used in injection molds, greatly reducing the cost of machining these configurations of mold components. Is to make it.

5. Process of the second embodiment

In operation, when the mold is closed and clamping tonnage is applied to the mold, the forming stack 102 aligns its components as follows. The gate insert 150 fits inside the cavity 151 by positioning the diameter portion (not shown), and the cavity female taper 164 aligns the corresponding male taper 165 on the neck ring insert 152. And neck ring female taper 166 aligns corresponding male taper 167 on the core. The core 153 has a corresponding tolerance at the core base 159 without allowing the spring loaded fastening means to allow some movement at the base of the core and the core spigot 168 without jeopardizing the sealing of the core cooling circuit 169. The core 153 can be moved to conform to this taper alignment method. Element 161 may be used as a sensor and / or actuator as described above.

6. Structure of the third embodiment

Figure 5 illustrates one problem that may occur when forming thin walled parts using a forming stack. If the incoming resin flow does not fill the cavity precisely symmetrically (ie, when the flow takes an optional course 190 as it flows down the sidewall), the resin is core 191 as indicated by arrow A. Unbalanced lateral force can be applied to the core, thereby causing the core to move inside the cavity 192. Subsequent molded parts have non-uniform sidewall thicknesses that may be walls thin enough to be defective.

An embodiment for overcoming this problem is shown in FIGS. 6 and 7 showing the thin-walled stack 103. The thin wall forming stack 103 includes a cavity 180 and a core 181. The core has several spring loaded fasteners (eg, bolts 183, washers 184 and spring washers (bellvilles) 185) used to fasten the core 181 to the core plate 182. The male taper 186 on the cavity is used to align the core 181 through the female taper 187. The core can adjust its position relative to the core plate as described above. An annular recess 188 in the core base is used to receive the piezoceramic element 189 having the wiring connection 190. The wire connector 190 may optionally be connected to the controller 193. There is some tolerance between the base of the core 181 and the core plate 182. FIG. 7 shows a top view of the core assembly of FIG. 6 and shows the arrangement of multiple elements 189 in annular form. Eight elements 189a-h are shown with individual wiring connections. In this embodiment, each element forms an arc of approximately 45 degrees. Naturally, any number of elements having the same or different shapes may be used as desired.

7. Process of the third embodiment

As described above with respect to the embodiment and core shifting problems shown in FIGS. 6 and 7, it may be offset by selectively energizing one or more piezoceramic force generators 189a-h within the base of the core 181. have. By analyzing the position of the unbalanced sidewall of the previous molded part and determining the direction in which the core was moved to form the part, a suitable device 189 or combination of elements 189a-h was used to counteract the core ( It can also be energized to apply a countering force, minimizing core shifting in subsequent molding cycles. By selecting the combination of elements 189 or elements 189a-h and the amount of voltage each to be applied to the element, an appropriate offset force (in terms of both intensity and position) can be applied. The next molding material may be further analyzed to fine tune the countermeasures until the wall thickness of the part is corrected within acceptable limits.

8. Structure of the fourth embodiment

FIG. 8 shows a fourth embodiment of a thin wall forming stack applicable to other preferred embodiments introduced herein, as well as additional configurations that would be appreciated by those skilled in the art. The sensor elements 110a-h and actuator elements 189a-h are mounted adjacently and configured to act as a sensor in which one element monitors the dimensional change of another element configured as a motor, so that real-time closed loop control It can be executed by simultaneous operation of the devices. This configuration allows for immediate detection of the unbalanced compressive force and corrects it quickly. Each sensor element 110a-h may be used to detect a compressive force between the core and the core plate and / or a change in adjacent piezoelectric actuators 189a-h. When mounted in close proximity, these sensors and actuators may also be used to monitor the compression force between the various injection molded components as described above.

In this thin wall formed stack embodiment, the group of sensor elements 110a-h is preferably located laterally (inward in the radial direction) next to the group of actuator elements 189a-h. It is also within the scope of the present invention to depart from this preferred configuration, such as for example to position the sensor element radially outward of the actuator element or any other configuration that forms a closed loop feedback system. The signals sent by the sensors in this group correspond to the amount and position of the shifting occurring, and the signal calculates the appropriate offset energy level so that an offset force can be applied to substantially correct the core shifting occurring. Is sent to a controller 193 that can communicate to elements 189a-h. Signal processing and controller performance is fast enough to allow this application of this correction method to correct the core shift with a real time feedback loop.

9. Conclusion

As such, what is described is a method and apparatus for using active material elements independently and in combination in an injection molding machine to achieve useful improvements in injection molding apparatus and to minimize mold warpage and misalignment.

Advantageous features according to the invention are: 1. an active material element used singly or in combination to generate or detect force in an injection molding apparatus, 2. 2. of bending of a molding apparatus by a closed loop controlled force generator. Offset, 3. Correction of core shifting in the molding apparatus by a locally applied force generator that applies a predetermined force calculated from data measured from previous molded parts.

While the present invention provides a distinct advantage over injection molded parts that generally have a circular cross-sectional shape that is orthogonal to the part axis, those skilled in the art will appreciate that the present invention is possibly possible, such as in buckets, paint cans, parts boxes, and other similar products. It will be appreciated that it may be equally applicable to other molded articles having circular cross-sectional shapes. All such molded products are included within the scope of the appended claims.

The individual components shown as outlines or represented by blocks in the accompanying drawings are all known in the art of injection molding, and their specific construction and operation are not critical to the operation or optimal mode for carrying out the invention.

While the present invention has been described with respect to what is presently considered to be the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiment. On the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims (41)

Apparatus for injection mold having a core and a core plate, An active material sensor disposed between the core and the core plate and configured to sense a force between the core and the core plate to generate a corresponding sensing signal; A wiring structure coupled to the active material sensor and configured to transmit a sense signal in use Device comprising a. The apparatus of claim 1, wherein the active material sensor comprises a piezoelectric sensor. The apparatus of claim 1, wherein the active material sensor is configured to be disposed in an annular groove of at least one of the core and the core plate. The apparatus of claim 1, further comprising a plurality of active material sensors configured to be disposed at different locations between the core and the core plate. The apparatus of claim 1, further comprising a processor configured to receive a sensing signal from the active material sensor and to generate at least one of (i) a clamping force signal, (ii) an injection pressure signal, and (i) an injection speed signal. . The apparatus of claim 1, further comprising an active material actuator configured to be disposed between the core and the core plate, the active material actuator configured to receive an actuator signal and apply a response force between the core and the core plate. 7. The apparatus of claim 6, wherein the active material actuator comprises a piezo electric actuator. 7. The method of claim 6, wherein the active material actuator is disposed adjacent to the active material sensor, the active material sensor configured to detect a change in the dimension of the active material actuator in response to a change in distance between the core and the core plate. Device. 7. The apparatus of claim 6, further comprising a plurality of active material actuators configured to be disposed at different positions between the core and the core plate. 10. The apparatus of claim 9, wherein the plurality of active material actuators are configured to control the bending of the core plate. 10. The apparatus of claim 9, further comprising a plurality of active material sensors configured to be disposed at different positions between the core and the core plate, wherein the injection molding machine comprises a plurality of cores, at least one active material sensor and at least one active The material actuator is configured to be disposed adjacent each core. 12. The apparatus of claim 11, further comprising a control structure configured to (i) receive a sense signal from the plurality of active material sensors, and (ii) transmit an actuator signal to the plurality of active material actuators. The apparatus of claim 12, wherein the control structure is configured to perform closed loop control of pressure between the core and the core plate. A control device for an injection mold having a first surface and a second surface, An active material sensor configured to be disposed between a first surface and a second surface of the injection molding machine, the active material sensor sensing a compressive force between the first surface and the second surface and generating a corresponding sensing signal; A transmission structure configured to transmit a sense signal from the active material sensor in use Control device comprising a. 15. The method of claim 14, further comprising an active material actuator configured to be disposed between the first surface and the second surface, the active material actuator receiving an actuation signal and generating a corresponding force between the first surface and the second surface, And the transmitting structure is configured to transmit an actuation signal to the active material actuator. The control device of claim 15, wherein the active material sensor and the active material actuator each comprise a piezoelectric element. 17. The control device of claim 16, further comprising a plurality of piezoelectric sensors and a plurality of piezoelectric actuators, each configured to be disposed between the first surface and the second surface. A device for controlling the warpage between the first and second surfaces of an injection molding machine, A piezoceramic actuator configured to be disposed between the first and second surfaces of the injection molding machine, the piezoceramic actuator receiving an actuation signal and generating an expansion force between the first and second surfaces; A transmission structure configured to transmit an actuation signal to the piezoceramic actuator Device comprising a. 19. The apparatus of claim 18, further comprising a piezoceramic sensor disposed adjacent to the piezoceramic actuator to detect a change in dimensions of the piezoceramic actuator to generate a corresponding sensor signal. 20. The apparatus of claim 19, further comprising a processor structure for receiving a sensor signal from the piezoceramic sensor and transmitting an actuation signal corresponding to the piezoceramic actuator using closed loop control. 21. The apparatus of claim 20, further comprising a plurality of piezoceramic sensors and a plurality of piezoceramic actuators, each configured to be disposed between the first and second surfaces of the injection mold. A device configured to be disposed between two adjacent load bearing surfaces of an injection molding machine, Configured to be disposed between two adjacent load bearing surfaces of the injection molding machine, (i) sensing the compressive force between two adjacent load bearing surfaces of the injection molding machine and generating a corresponding sensing signal, and (ii) A piezoelectric element configured to perform at least one of receiving an actuation signal and causing the distance between two adjacent load bearing surfaces of the injection molding machine to be adjusted; A transmission structure configured to perform at least one of (i) receiving a sense signal from a piezoelectric element and (ii) providing an actuation signal to the piezoelectric element. Device comprising a. The device for correcting core shifting in an injection molding machine having a core and a core plate, A plurality of piezoelectric actuators configured to be disposed around the periphery of the core, the plurality of piezoelectric actuators respectively configured to generate and separately control the expansion force between the core and the core plate, In use, a transmission structure configured to provide an actuation signal to each of the plurality of piezoelectric actuators; In use, a control structure configured to provide an actuation signal to selected ones of the plurality of piezoelectric actuators to correct core shifting. Device comprising a. 24. The apparatus of claim 23, further comprising a plurality of piezoelectric sensors configured to be disposed around the periphery of the core to respectively detect a compressive force between the core and the core plate to generate corresponding sensing signals, wherein the transmission structure comprises the control structure. A device configured to transmit a sense signal to the device. The apparatus of claim 24, wherein each piezoelectric sensor is disposed adjacent to a corresponding piezoelectric actuator. A method of controlling an injection mold having a first surface and a second surface, Detecting a compressive force between the first and second surfaces with an active element sensor disposed between the first and second surfaces of the injection molding machine, Generating a sensing signal corresponding to the sensed compression force; Transmitting a sense signal from an active element sensor to a processor; Generating an injection molding machine control signal in accordance with the transmitted detection signal How to include. 27. The method of claim 26, wherein the active element sensor comprises a piezoelectric sensor. 27. The method of claim 26, wherein the control signal comprises at least one of (i) clamping force signal, (ii) injection pressure signal and (iii) injection speed signal. The method of claim 26, Calculating an operation signal corresponding to the transmitted detection signal; Using an active material actuator to generate an expansion force between the first and second surfaces corresponding to the actuation signal How to include more. 30. The method of claim 29, wherein the active element actuator comprises a piezo electric actuator. 27. The method of claim 26, further comprising disposing a plurality of piezoceramic sensors and a plurality of piezoceramic actuators between the first surface and the second surface. A method of controlling an injection mold having a first surface and a second surface, Determining a force actuation signal to control the space between the first surface and the second surface; Transmitting a force actuation signal to a piezoelectric actuator disposed between the first and second surfaces of the injection molding machine; Using a piezo electric actuator to generate a corresponding expansion force between the first surface and the second surface How to include. 33. The method of claim 32, further comprising determining a force actuation signal from a previous molding act. 33. The method of claim 32, Using a piezoelectric sensor to sense the compressive force between the first surface and the second surface; Generating a sensing signal corresponding to the sensed compression force; Transmitting the detection signal from the piezoelectric sensor to the controller How to include more. The method of claim 34, wherein Using the piezo electric actuator to detect a dimensional change of the piezo electric actuator and generate a feedback signal corresponding to the detected width change; Real-time closed loop control of the piezoelectric actuator according to the feedback signal How to include more. A device for correcting core shifting in an injection mold having a core and a core plate, A plurality of active material actuators configured to be disposed around the periphery of the core, the plurality of active material actuators respectively configured to generate and independently control expansion forces between the core and the core plate when energized; In use, control means configured to provide an actuation signal to each of the plurality of active material actuators; A user interface configured to accept user input, The user input is input to the interface based on measurements taken from molded parts previously produced by the injection mold and the control means provides the actuation signal based on a user input. 37. The apparatus of claim 36, further comprising a plurality of active material sensors configured to be disposed around the periphery of the core, the plurality of active material sensors respectively sensing a compressive force between the core and the core plate to generate corresponding sensing signals. And configured to transmit to the control structure. 38. The apparatus of claim 37, wherein each active material sensor is disposed adjacent to a corresponding active material actuator. Molds for use in injection molding machines, Core plate, Core halves, With a joint class, At least one active material element provided inside said core half A mold comprising a. 40. The mold of claim 39 wherein the at least one active material element comprises an actuator and generates a force between the core plate and the core half. 40. The mold of claim 39, wherein the at least one active material element comprises a sensor for sensing a force generated between the core plate and the core half.

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